A. Field of the Invention
The present invention generally relates to fluid dispensers, and, more particularly, to a new and improved method and apparatus for dispensing a non-compressible fluid substance, for example, a topical dental preventative medicine, in variable amounts by means of a handheld, finger operated, piston-cylinder type dispenser.
B. Description of the Prior Art
Currently periodontal disease affects approximately three out of four adults in the United States over the age of thirty-five years and is responsible for at least seventy percent of all tooth loss in adults. Typically, the disease progresses from an early, reversible stage, known as gingivitis, to a later, irreversible stage, known as periodontitis, in which both teeth and bone are destroyed. Common treatment for periodontal disease involves removing the bacterial colonies by scraping or surgery, operations performed by licensed periodontal dentists. A person can reduce his chances of experiencing periodontal disease by proper tooth care, including regular brushing and flossing, and by periodic dental visits.
More recently, researchers have been investigating topical dental preventative treatment medicine. For example, the oral compositions disclosed in U.S. Pat. No. 4,515,771 when topically applied to the gumline on a regular basis effectively eliminates the bacteria associated with gingivitis. Such treatments typically have been applied in clinical studies by dentists using professional applicators.
The periodic and timely application of a topical periodontal medicine can save a person much pain and expense. However, daily visits to a dentist are impractical for the contemplated widespread use of the oral compositions disclosed in the above-mentioned '771 patent. Therefore, a need exists for a simple, inexpensive applicator that a person can use at home on a frequent basis.
Applicators for dispensing non-compressible fluid substances, for example, topical dental medicines of the type disclosed in the '771 patent, are old and well known in the prior art as exemplified by not only the dispenser disclosed in the '771 patent and described therein as being capable of being used by either a professional or the patient himself, but also in the following U.S. Pat. Nos. 1,410,530; 2,086,462; 2,505,028; 2,752,920; 2,847,009; 2,875,761; 3,051,172; 3,161,323; 3,164,303; 3,220,413; 3,581,399, 3,900,954; 4,295,828; 4,330,280; 4,391,590 and 4,641,766. Most of the prior art applicators disclosed in the above patents are relatively complex and expensive and are awkward and generally not suitable for use by a patient on himself because, generally, they were designed to be used by one person on another person.
For example, the device disclosed in the '530 patent is a pump for use in evacuating blood from body cavities during surgery. The '462 patent discloses a dental instrument for discharging wax or other material that utilizes a rack or indexing rod having a plurality of preformed, spaced apart teeth and a pivotal pawl for advancing the rod along an elongate axis to dispense on a repetitive basis a predetermined amount of wax, the amount being determined by the spacing between adjacent preformed teeth.
The '028 patent, the '920 patent, the '009 patent, the '761 patent, the '303 patent, the '413 patent, the '399 patent and the '954 patent all disclose piston-cylinder type dispensers for dispensing non-compressible fluid substances having in-line piston rods or plungers disposed for movement along the central axes of the cylinders. The force used to dispense the fluid substances from the devices disclosed in these patents is applied by a hand or finger to the end of the piston rods or plungers. These prior art devices, while suitable for some purposes, are difficult for a generally unskilled person to use on himself, particularly in applying a topical dental medicine on his own gums.
The '828 patent, the '280 patent and the '590 patent all disclose piston-cylinder type dispensing apparatus used in conjunction with two-piece, manually engageable handles for applying force to the ends of and generally along the longitudinal axes of the piston rods of the apparatus. Again, these prior art devices are awkward to use for certain purposes, for example, in applying topical dental medicine to one's own jaws.
The '172 patent and the '323 patent disclose piston-cylinder type fluid substance dispensers having similar, somewhat complex mechanical systems for applying force to dispense the fluid substances. Specifically, the dispensers of these patents utilize elongated index rods or racks with a plurality of preformed, spaced apart teeth and pivotally mounted pawls for advancing the piston rods in predetermined, precise steps, thereby dispensing the same amount of the fluid substances on a repetitive basis. In addition to being mechanically complex, the devices of these patents are not readily adapted to be used by a person in dispensing a fluid substance, for example, a topical dental medicine, on himself.
The '771 patent, discussed above, discloses a somewhat complex, electrically driven dispensing device for use by a patient or a professional in applying the topical dental preventative medicine disposed therein to the gums of a patient. In addition to requiring a supply of batteries to power the dispenser, it is believed that the configuration of the dispensing apparatus may not be the most efficient for use by a patient in dispensing a topical dental medicine on his own gums.
The '766 patent also discloses a piston-cylinder type dispensing apparatus utilizing a piston rod having a plurality of preformed, equally spaced teeth disposed along its length. The preformed teeth on the piston rod cooperate with a pair of actuating arms pivotally secured to the cylinder body to dispense on a repetitive basis the same amount of a fluid substance.
While suitable for some purposes, all of the above prior art dispensers have one or more drawbacks that render them unsuitable for other purposes. More specifically, a need exists for an economical, simple, easy to use dispenser for use by a patient in applying topical dental medicine to himself at a rate controlled by the skill and desire of the patient.